christiane amanpour is in jerusalem, but we begin with alex marquardt in gaza city. alex. >> reporter: good morning, bianna. overnight the israeli air force targeted media buildings here in gaza while the shells not very far from here. the big question, whether a cease-fire will be able to be brokered before israel launches a ground invasion. israeli jets pummeling gaza overnight. two buildings housing hamas and international media were targeted. six journalists were wounded. from the sea, volley after volley of naval artillery hit alleged terror sites. so far, more than 50 palestinians have been killed and more than 500 wounded. "we're exacting a heavy price from hamas," said israeli prime minister benjamin netanyahu, and the military is prepared for a significant expansion of its operations. for days, tanks and troops have been building up along the border ahead of a possible invasion. far fewer rockets were fired from gaza overnight, but this morning, sirens wailed in tel aviv as hamas fired two rockets. both intercepted by the iron dome anti-missile system. three